US1745038A - Telephone system - Google Patents

Description

Jan. 28, 1930.

A. J. RAY 1,745,038 TELEPHONE SYSTEM Filed Sept. 29, 1927 8 Sheets-Sheet 1 QR S T5 SK PCR TCR FL RS RIK RH 63 TIUETL D1" Hfihur l Jan. 28, 1930. A, 'J RAY 1,745,038 I TELEPHONE SYSTEM Filed Sept. 29. 1927 8 Sheets-Sheet 2-.

Jan. 28, 1930. J, RAY 1,745,038

TELEPHONE SYSTEM Filed Se pt. 29. 1927 8 Sheets-Sheet 3 13 1 mm J. E: %f i Jan. 28, 1930. A, J, R-Ay U 1,745,038

TELEPHONE SYSTEM Filed Sept. 29. 1927 8 Sheets-Sheet 4 Jan. 28, 1930.

A. J. RAY

TELEPHONE SYSTEM Filed Sept. 29.. 1927 8-Sheets-Sheet 5 Jan. 28, 1930. RAY 1,745,038

TELEPHONE SYSTEM,

Filed Sept. 29, 1927 s Sheets-Sheei 6 Imren u Jan. 28, 1930. A- J RAY 1,745,038

TELEPHONE sYsTsm Filed Sept. 29, 192'? s Sheets-Sheet 7 Jan.- 28, 1930. A. J. RAY I 1,745,038

TELEPHONE SYSTEM Filed Sept. 29, 1927 8 Sheets-Sheet 8 Patented Jan. 28, 1930 neural) STATES PATENT O ARTHUR J. RAY, or oirrc' eo, ILLINOIS, ssisnon roAssocrArn-n TELEP ONE Ann 7 TELEGRAPH COMPANY, or KANSAS CITY, MISSOURI, A conrgonArzoiv or DELAWARE TELErHonn I SYSTEM Application filed September 29, 1927,1'Sria1 No. 222,741, and in. Great Britain October 14, 1926.

The. present invention relates to telephone systems and is more particularly concerned with what is known as routine testing appara tus, that is to say apparatus arranged to re produce automatically the actual conditions of use for each unit in turn of a large group of similar pieces of apparatus. The invention a'lsois intendedto be applied more particularly to the testing of apparatus which can 10 only be tested while it is not actually in use and must not be busied to its normal means of access in order that a test may take place. It is generally recognized nowadays that routinetesting is'desirable, it" not essential,

particularly for complicated apparatus, 111

be tested. Thisclearly presents a difficulty in order that it may be possible to anticipate faults rather than correct them after they occur, and for the test to be effective itis essential that every piece ofapparatus'shall the above-mentioned circumstances, and it is the main object of the ln'ventlon to deal with cases'ot this sort in a s mple manner.

According to one feature" ofthe invention in V an automatic testingarrangement havinga 0 piece of apparatus is adapted to be prevented I hunting switch for associating with the test.-

ing equipment the various pieces of apparatus to be tested, idlepiec'es of apparatus are tested in turn until all have been dealt with and a from seizure by the hunting switch inconsequence of a special potential associated there with due to the completion of the test;

A further feature of the inventionis the 5 provision of an automatic testing arrangement for the routine testing oftelephone apparatus when Such apparatus isnotin use in which means associated with the testlng equipment enable part cular pieces of appara in use So that certain tests may be carried out in conjunctionwith the user ofthe apparatus,

" stood from the following description of one method of carrying the invention into effect which should be taken in conjunction with the accompanying drawings. Clearly any routining arrangement will need to be'specially de signedin view of the apparatus it is desired tu s to be associated withsaid equipment when I to test and the arrangement shown has been over an order wire are setup on asingle set of digit keysthe operation of which serve to control an impulse sender to send out the necessary trains of impulses for operating automatic switch-es to connect with the wanted line. As a general rule the B operator will have L0 trunks incoming to her position, though in particular cases this number may be increased to 50. Moreovenin view of the fact that the complete operation of an impulse sender takes several times aslong asthe set, ting of the digit keys, it is arranged that as i many as" four impulse senders; can be associated withher positlon at a time in order that she may workcontinually at full speed,

the impulse senders being accessible in com-1 I mon to a considerable number'of operators.

The testing of the complete apparatus falls naturally into two parts, one comprisingthe testing of the actual impulse senders which may be done as described'in British Patent No. 267,606 and the other the testing of the junction relay sets and apparatus for associating impulse senders with the operators keyset. A-little consideration will Show that for a complete test to be carried out it is necessary v to employ the apparatus at the operators position used for associating an idle impulse sender with that posltiomhence it follows that the test cannot be carried out while the position is in service.

Referring now to the drawings comprising Figs, 1-8 ;F1g's. 1 and 2 Show the various con trolling keys and a number of the associated relays; Figs. 3 and tshow a further group of the relays controlling the ro'utiner; Figs. 5 and 6 show the test switch TS, the ro'utine'in- I dicating switch R18 and the number-set-up switch NS, together with the fault indicating lamps for indicating the progress of aparticular test; while Figs] and 8 Show the distribution equipmentvbymeans of which connect-ion is made with each position in turn, and also with each 1unct1on in turn at a'par ticular position. In order to facilitate the understanding of the circuit, the description will be divided into two parts, firstly consideration of the arrangements by which connection is made in turn to the various positions and each junction at the position is tested, and secondly consideration of the actual tests which are carried out on the junction and the circuit arrangements by means of which they are applied.

Considering first, therefore, the distribution equipment in the arrangement shown, it is assumed that the test set is to serve for 60 operators positions and that each position has 50 incoming junctions and means for associating four impulse senders with the position at a time. The position distribution equipment comprises a primary distributor PD from which access is had to three secondary distributors SD SD of which only SD and SD are shown since the circuits of SD are similar. Preferably the contacts of the primary distributor PD are multipled round the bank as shown in Fig. 7, so as to avoid unnecessary operation of the switch. Since it is not found possible to provide the secondary distributors with sufficient wipers for all the functions which they are required to perform, each one has associated with it an auxiliary secondary distributor of which only the auxiliary secondary distributor ASD associated with the switch SD is shown in Fig. 8. Each secondary distributor is wired to have access to 20 operators positions and when all .the 20 have been tested or found busy, the

primary distributor is advanced so as to connect up the succeeding secondary distributor. Associated with each position are a pair of junction distributors such as JD and JD .shown in Fig. 8, which are given access to a maximum of 24 and 22 junctions respectively. \Vhere the full 50 junctions are equipped, access is obtained to the last four over the first four contacts of the distributor JD a suitable switching operation being performed to connect these junctions up in place of junctions 14 as will be described subsequently. The junction distributors are provided with a normal position in which the contacts are left dead and by this means the wipers of the junction distributors associated with all the positions may be inultipled together to the routine test set and the position distributors ensure that the juncton distributors of only one position shall be operated at a time. It should be mentioned with reference to Fig. 7 that the banks of wipers 618-620 of the secondary distributor SD are wired to the various junction distributors in the same manner as is indicated by the wiring of the first contacts in the banks of SD. The bank of Wiper 617 is wired to the contacts of the associated position battery feed relays wh le that of wiper 621 is wired to the bank of the associated auxiliary secondary distributor completed for changing over from junctions 1-4 to junctions 4;" 50 where this is necessary. The other auxiliary secondary distributors are wired in a similar manner. The bank of wiper 625 of the unction distributor J D is wired to the lamp leads of the various junctions, that of wi er 626 to the respective assignment leads an those of wipers 627 and 628 to the negative and positive trunk conductors respectively.

The operations involved in making a test will now be considered in detail. In order to set the routiner in operation, the attendant operates the start key SK whereupon a circuit is completed for relay 115. Relay 115 upon operating, at armature 116 prepares a circuit for the test relay 131, at armature 117 completes a circuit for the relay 119 and at armature 118 prepares the pulsing circuit to the first secondary distributor. Further, at armature 122 relay 115 completes a circuit for relay 127 which extends as follows: battery, winding of magnet 507 of the switch TS, lead 439, armature 313 and its back contact, lead 726, lead 441, interrupter contacts 508, wiper 506 and its normal contact, lead 93, winding of relay 127, armature 122 and its front contact. Relay 119 now operates and at armature 120 opens the circuit of relay 280 which is normally energized in the following circuit: battery, relay 280, lead 698, lead 407, normal contact and wiper 622 of the switch SD normal contact and wiper of the switch SD represented by the link 624, normal contact and wiper 616 of the switch SD lead 18, lead 664, armature 120 and its back contact to earth and at the front contact of armature 120 extends earth over lead 686, lead 26, wiper 603 of the primary distributor PD, lead 23, winding of relay 215 to battery so that relay 215 is operated and prepares circuits for the junction distributors and auxiliary secondary distributor and also for the relay 185. Furthermore at armature 121 relay 119 prepares a circuit for stepping the junction distributors. At armature 129 relay 127 prepares circuits for relays 152' and 180 and at armature 130 closes the pulsing circuit of the secondary distributor. Relay 119 moreover at armature 123 opens the homing circuit of the primary distributor and provides a locking earth, at armature 124 prepares a circuit for stepping the primary distributor after each secondary distributor has rotated over all positions connected to it, at

armature 126 opens an alarm circuit over lead 57 V and at armature 12 5 *co'nnects earth to motor start lead '94 and opensj'the normally closed circuitf r relay 27 8' which extends as follows: battery, winding of'relay 278, lead 714,"l'ead 493, lead 845,'link 649 representing wipers and norlnalicontacts of all the junc tion distributors not shown, normal contact and wiper 637, norinal contact and wiper 630, lead 1, lead 665,back contact and armature toearth. Relay'278 now de-energizes thereby altering certain supervisory circuits as will be described subsequently. The

pulsing circuit completed on the operation of relay 127 extends from earth, winding of relay 264, armature 267 and its back contact,

lead 47, armature 148 and 'its back contact,

lead 61, back contact and armature 286, lead 62, armature 13 6 and its back contact, arrnature 118 and its front contact, front contact and armature 130, armature 153 and its back contact, armature 167 and its back contact,

lead 666, lead 27, wiper 605 or" the primary distributor and the first contact in its bank,

winding of magnet 610 of the secondary discircuit for the slow-to-pull-up relay 266 which upon operating in due course,r,at arniature 267 opens the circuit originally traced, whereuponrelay 264 and magnet 610 fall back and the latter advances thE'SWltCll SD one step. Relay 264 upon releasing, opens the circuit of relay 268 and this in turn brings down relay 266 whereupon unless the opera-v .1

tors position then connected with is in con dition to be tested, magnet 610 is again energized and the cycle recommences. Therelay 533 in Fig.1 6 is used for feeding battery to v the operators headset and when the operator is absent from the position and has therefore withdrawn her headset plug, relay 533 is deenergized and extends earthover armature 534 and lead 408 to the first contact in the bank of the secondary distributor Sl over which access is obtained to this position. It

will be understood that the battery feed relays ot' the other'operators positions are connected up similarly to other contacts in the banks oiithe' switches SD SD The secondary distributor continues to advance step by-step owing to the pulses received from relays 264, 266 and 268 until wiper 611 encounters a contact to which earth is'connected owing to the operatorjbeing absent from the corresponding position. Thereuponthe follo'wingcircuit is completed: earth connected to this contact over the back contact and armature of the battery feed-relay wiper 611, first contact in the bank of wiper 601 and saidiwiper, lead 24, lead 691, lead 59, arinature 289'and its back contact, lead 60, back contact and armature 160, back contactand armature "145, armature 116 and -;its front contact, winding of relay 131, resistance'276 to battery. Relay 131 is operated in this circuit and at armature 133'prepares a circuit for the magnet 631 of the unction distributor J D at armature 134 completes a c'ircuit'tor relay 152, at armature 135 closes another-:

point in the cirouitofrelay and at armature 136 disconnects the pulsing earth from the magnet ofthe secondary distributor SD? and extends it to the'magnet of the auxiliary secondary distributor ASD over lead 676, front contact armature 218, armature 191 and its back contact, lead 2, magnet 647, lead 840, lead 29 to battery through relay 233. Consequently the auxiliary secondary distributor now commences to step and this con tinues until relay is energized when'the auxiliary secondary distributor reaches the same position as its associated secondary distributor. The circuit for relay 185 may be traced from earth, wiper 604 and its first contact, wiper 615, multipling to wiper 646, lead 3, armature 219, and its front-contact, windr of relay 185-to-battery, andthe operation of the relay opens the stepping circuit at' armature 191. When relay 152 operates, at

armature 153 it opens another point in the pulsing circuitito the-secondary distributor,

' at armature 155i completes a locking circuit fo'rfitself which extends" as follows: battery, winding "ofrelay 152, armature 155 and its 1 front contact, normally closed right-hand springs'of the re-start key RS,ar1nature 169 and its baokcontact, front contact and arma- I ture 123 .to, earth, at armature 156 opens a. point inthe circuits of the relays 137, 143 and 162,'an'd at armature 157 prepares a circuit for'horning the unction distributors. -T he operation of relay 185 also at arinatures186- 189 and 192 and 193 prepares the connection lli) of thedi'git'andorder wire leads overleads 79'82 and 9 and 10'to' the wipers of the auxiliary secondary distributor, and atarrnature completes a circuit for relay 180'eX- tending as follows: battery,-winding of relay 180, front, contact and armature .190, lead 67 1,-front"contact and armature 135, armature 129 and its front-contact, front contact andarm'ature 134, armature-169 and its back contac't,:tront contact and armature 123 to earth. -Relay 180 upon operating,at arrria- T ture181 completes a circuit for relay 229 and Ithisflocks 'up'by way of armature 230, at i armature 182 completesthe following circuit 5 for relay 330; battery, winding ofrelay 330,

lead 45, lead 683, armature 182 and itsfront" contact, lead 682,1ead 33, wiper 502 of the switch'TS andthe first contact in its bank,

lead 453 and-by-way of interrupter 485 to earth. Moreover at armature 183 earth is connected over leads 679 and 44, armature 331 and its back contact, lead 725, upper winding of supervisory relay 314 to battery, and at armature 184 the homing circuit of the test switch TS is Opened and earth is connected to wipers 501 and 503. Vhen the contacts of interrupter 485 next close, relay 330 is operated and at armature 331 opens the circuit of the relay 314, at armature 332 completes a direct circuit for magnet 507 and at armature 333 completes a locking circuit for itself extending as follows: earth, armature 332 and its front contact, lead 441, inter rupter contacts 508, lead 429, armature 333 and its front contact, winding of relay 330 to battery. The connection of earth to wiper 501 completes a circuit for the first supervisory lamp 542 over lead 753, which lights to indicate that a free position has been found. Vhen magnet 507 has operated fully and opened interrupter contacts 508, relay 330 de-energizes thereby opening the circuit of magnet 507 so that the switch TS is advanced one step. The earth connected to wiper 503 is now extended over lead 440, lead 35, back contact and armature 163, armature 121 and its front contact, front contact and armature 133, lead 667. armature 176 and its back contact, armature 216 and its front contact, lead 20, wiper 613 and the first contact in its bank, lead 806, magnet 631 of the junc tion distributor JD lead 402, winding of supervisory relay 295 to battery so that magnet 631 is operated. The succeeding pulse from interrupter 485 again operates relay 330 and this in turn effects the advance of the test switch. Vhen the test switch takes its next step and advances to its third position, the circuit just traced is opened and accordingly the wipers of the junction distributor JD are advanced one step. In case the position which has been connected with should only just have been vacated by the operator so that there is a call still in progress over the first junction, there will be earth on the lamp lead and this will accordingly be extended over the appropriate contact in the bank of wiper 625, lead 13, lead 74, lead 720, armature 340 and its back contact, lead 721, upper winding of relay 376 to battery. Moreover owing to the advance of the test switch, the initial circuit over lead 440 is opened and relay 334 is operated over wiper 503 and lead 443. Accordingly the following circuit is now completed: earth. relay 264, armature 267 and its back contact, lead 711, armature 379 and its front contact, lead 710, armature 335 and its front contact, lead 35 and thence over the circuit previously traced to the magnet of the junction distributor JD Consequently this switch is again operated and if one or more further busy junctions are encountered, relay 376 remains operated so that the movement continues until the switch J D has been moved into engagement with a j unction over which no call is in progress. Relay 376 will then de-energize and complete a circuit for advancing the test switch which now continues its operation and applies the various tests in turn to this junction as will be fully described subsequently.

\Vhen wiper 503 has made a complete revolution and again comes into engagement with the second contact in its bank, the circuit traced above again becomes operative for advancing the junction distributor, and in the ordinary course this will take only one step and the next junction will then be connected up for testing purposes. In case, however, this junction should still be in use or should be out of service for any reason, there will be earth on the lamp lead and this will operate relay 376 to step the junction distributor on past this junction as above described.

As already pointed out, the switch JD is arranged to deal with 24 junctions, and when its wipers are advanced into engagement with the last of these junctions, the following circuit is completed: earth, wiper 629 and the 24th contact in its bank, lead 12, winding of relay 172 to battery. Relay 172 upon operating, at armature 173 shunts armature 176 and its back contact and at armature 174 completes a circuit for relay 175. The latter upon operating, at armature 178 locks to earth at armature 123, at armature 176 prepares a circuit for the magnet 638 of the junction distributor JD, and at armature 179 prepares an auxiliary circuit for the magnet of the junction distributor JD \Vhen the testing of this junction has been completed and the test switch again reaches position 2, earth is again connected to lead 440 and is extended to the magnets of both distributors JD and JD hence JD is advanced to its 25th or normal contact and J D takes one step and tests the first junction in its bank. \Vhen the switch J D steps, the circuit of relay 172 is opened and it thereupon releases and prevents any further pulses being sent to magnet 631. If the first junction in the bank of JD is idle and in service the usual tests are carried out thereon and the switch JD is advanced one step to connect up a succeeding junction.

Vhen all the junctions accessible from the bank of the switch .11) have been tested, the switch wipers will be advanced to position 23 whereupon a circuit is completed as follows: earth, wiper 636 and the 23rd contact in its bank, lead 11, lead 669, winding of relay 166 to battery. Relay 166 upon operating, at armature 167 opens a point in the circuit for stepping the secondary distributor, at annature 169 opens the circuit of. relays 109, 152, 175 and 180, at armature 170 closes a point in the circuit of relay 285 and at armature 171 completes a. circuit for stepping the junction distributor JD a further step. \Vhen relay 180 de-energizes, earth is supplied at lead 805, first contact in the'bank of-w1per armature 184 for homingthe test switch and when this reaches normal position, relay 127 is operated. Relay 175 being slow to release holds up for a moment and when'it de-energizes the wipers of the switch JD are advanced a further step and the circuit of relay 166 is then opened and it a slowly releases.-

With the wipers of J D in the 24th position, I

the following circuit: iscompleted: earth; wiper 636and the 24th contact in its bank,

612 and said wiper, first contact in the bank ofwiper 602 and said wiper,lead 25, lead- 673, armature 154 of relay 137,- and itsback; i contact to the lower terminal of the winding of relay 181. Since the, original earth connection to theother terminal of this winding is still intact, relay 131 is now short-circuited and accordingly de energizes, thereupon at armature 136 again connecting up'thepulsing circuit from relay 264 for advancmg the sec:

ondary distributor. ,Accordingly conditions are now similar to those obtaining wh'enL-the test was started and the secondary distributor SD hunts to find an idle position. When such a. position is found as indicated by the presence ofearth on theassociated contact in the bank of wiper 611, relay 131 again oper-g ates and at armature 136 completes the circuit for advancing the auxiliary secondary d1s-: tributor correspondingly. The appropriate on which tests are made asgbeiore. I

then be completed as. follows: earth, wiper 604 and the first contact inits banlt,-flwiper- 615fand the 21st contact in'rits bank,- lead 403, windingof relay 297 to battery. Upon the operation of relay 297 a circuit is completed.

from earth, armature 124 and its front contact, lead 689, lead 69, armature 298 andlts front contact, lead 168, winding rot-"magnet, 607 of the primary distributor, lead 29, wind-, ing of relay 233,150 battery as before. Mag n et 607 thereupon energizes but does not yetad-: Since'relay 131i is still not-operated a circuit is again com-- Vance its associated; wipers.

pletedfor advancing the secondary distributor S13 and wiper 615 accordinglyleavesits 21st contact. Consequently the CllOllliJgIfOI relay 297 is now opened-and its,,relelases, thereby opening the circuit forqthemagnet,

- 607 of the primary} distributor whichj'ad vances the wipers one step. The-secondary distributor SD? is thus connected up and the positions accessible overitsbankjare then tested in the manner previouslydescribed. When it arrives at position2l, a circuit is completed for advancing the primary dis-: tributor in the. same way as abovedescribed, nand accordingly the secondarydistributor to thefact that it is heldopen' at armature 231, relay 229 being operated at this time. Consequently the switch SD .continues to step in response to pulses from relay 264 until it'engagesiits 23rd contact whereupon a circuitis zcompleted from earth 'on wiper 604 asbe fore, lead 401, winding of relay 292 tobattery. Relay 292 upon operating at armature "293 opens thelocking circuit of relay 229, thus causing it to release andiat armature 294 extends earth fromlead 69 over above circuit is opened. due tow the further stepping of the distributor SD It has alreadybeen pointed out thatxthe tests on an operators position can only be made when the position'isnot in use andaccordinglyit will be clear that even ifthe routine testing is undertaken at times of light load aswould normally be the case, a single operationof the routinerwould be unlikely to test all the operators positions; It is unct1on distributor is then advanced one step: and if necessary hunts to find an idle junctio r therefore provided in 'the presentinstance that afterall positionshavebeen tested once for busy or 'idlecondition and'the idle ones dulyflroutined, the various positions. are againitest'ed, only on this occasion not only positions which are actually busy have to be 1 passed over but also those which have been "routined on the previous operation 'of the;

distributing switches. The necessary discrimination-is effected due to the position.

which the second junction distributortakes up when a position has been completely routined; Reference to Figs??? and 8fwill" show that inthis case earth is appliedover the 24th contact in thebank of wiper 636 of the junction distributor J 1) to thercontact associated with the position in the bank of wiper 612' andfthis will-have; the 'effectfof producing a short-circuit on relay'131, so that in the case of positionsac-tually in use no earth is supplied. to this. relay. and in the case 7 i of positions which "areanotwin' use but which.

have already been tested earth is supplied to both terminals of the relay so that in either 7 event the relay --isunable to operate; Ac-

cordingly it does not openthepulsing circuit 7 i I to. the. secondary distributor and this switch 1 stepsi overthepositionQ -It' willbe recalled" that when a free position is encountered, relay 131 operates andcompletesa'circuitfor I relay 180 andthis'in'turnoperates relay 229 which locks up clependentupon relay 280fand 292: Hence if all the secondary distributors shouldpass over the whole of their banks without finding any'position in a condition to be tested, relays 131, 180 and 229 will not be operated and in this case when wiper 621 of the secondary distributor SD engages its 21st contact, earth is extended over lead 15, armature 231 and its back contact, lead 685, lead 65, upper winding of relay 285 to battery. Relay 285 is a two-step relay and at this time only operates its light armature 290 thereby short-eircuiting its lower winding by earth on the left-hand contacts of the restart key RS. Then the secondary distributor SD receives a further pulse, the initial energizing earth is removed and relay 285 then operates fully over both its windings in series and is accordingly locked up to the re-start key BS. The operation of relay 285 at armature 291 completes a circuit for the routine finished lamp 284 and the lower winding of relay 314 in series and relay 314 operates with results to be described subsequently. Relay 285 moreover at armature 286 opens the normal pulsing circuit for the secondary distributors and auxiliary secondary distributors, at armature 288 opens an auxiliary energizing circuit for itself, at armature 289 opens a point in the circuit of relay 131 and at armature 287 connects earth to wiper 616 of secondary distributor SD This switch accordingly commences homing and when it has reached its normal position the homing earth is extended to the secondary distributor SD When this switch in turn has reached its normal position the homing earth is transferred to the switch SD and when this switch has returned to normal a circuit is again completed over lead 407 for relay 280. Relay 280 upon operating, at armature 281 opens a further point in the locking circuit of relay 229 and at armature 282 opens a point in the magnet alarm circuit.

In case the attendant discovers by operating the key RIK that a number of positions have still not been tested, he may leave the routining apparatus in this condition for an interval and then by operating the re-start key RS, again set it to hunt for and routine positions which have not yet been dealt with. When the re-sta-rt key is pressed, the looking circuit for relay 285 is opened and it releases thereby completing the pulsing circuit for the distributor SD. The operation now proceeds as before and continues until all three distributors again make a complete rotation without finding any position in condition to be tested. It will be noted that in these circumstances only the secondary distributors are restored to normal but not the junction distributors, since these switches indicate by their off-normal position that the associated position has already been tested.

When the start key is restored, on the completion of the test or at any other time the circuit of relay 115 is opened and upon deenergizing it opens the circuit of relay 119. Upon the de-energization of relay 119, a homing circuit for the secondary distributors is completed from earth over armature 120 and its back contact and leads 664 and 18 to wiper 616 of the distributor SD whence it is extended in turn to distributors SD and SD Over armature 123 and its back contact earth is applied over leads 688 and 28 to the bank of wiper 606 so that this is effective in bringing about the homing motion of the primary distributor. The earth over the back contact of armature 125 is extended over leads-665 and 1 to wiper 630 of the junction distributor J D and serves to efiect the homing motion of this switch. When the switch reaches its normal position, the homing earth is extended to the switch J D and this in turn is operated to normal. All the other unction distributors accessible to the routiner are homed in a. similar manner, one after the other, and accordingly all the apparatus is left in the position shown ready for a further test to be initiated, for instance the next day. The sole exception is the auxiliary secondary distributors for since they always follow their associated secondary distributors when they are required for use it is unnecessary to return them to a definite normal position. It may be mentioned also that with the arrangement shown, the operation of the key RS is necessary to bring down relay 285, but this could if desired be dependent on relay 115 so that it would release when the start key was restored.

Consideration may now be given to the actual tests which are made on each junction. The initial circuit for stepping the test switch TS has already been traced, this being comp eted owing to the operation of relay 330 when relay 180 is energized. It was pointed out, moreover, that with the test switch engaging its second set of bank contacts. a circuit is completed over lead 440 for advancing the first junction distributor of the seized position one step, the test switch meanwhile moving to engage its third set of contacts. In case the junction which is then connected with should. have a call in progress or should be out of service, there will be earth on the lamp lead and accordingly the junction distributor will again be advanced under the joint control of relays 334 and 376. \Vhen relay 376 deenergizes, a clrcuit is completed for relay 330 extending as follows: battery, winding of relay 330, lead 45, lead 683, armature 182 and its front contact,'lead 682, lead 33, wiper 502 and the third contact in its bank, lead 461. lead 736, back contact and armature 382. lead 735, interrupter'485 to earth, so that the switch TS is moved to fourth position. In this position a circuit is completed over the fourth contact in the bank of wiper 503 and lead 446 for relay 336. Upon the operation of relay 336, earth through the lower winding of relay 376 is connected over lead 7 24, front contact and armature 340, lead 720, lead 74, lead 13 and over wiper 625 of the switch J D to the lamp lead; if .this lead is continuous, battery through the lamp will be operative to energize relay 376. Moreover at armature 337 earth is connected over lead 7 09 through the winding of relay 389 and over lead 405 and wiper 628 to the positive trunk conductor. In case this trunk should be in contact with any adjacent leads, a circuit will now be completed for re lay 389 and it will thereupon operate. Fur thermore at armatures 338 and 339 the wind ings of relay 385 are connected together and over leads 718 and 404 and wiper 627tothe negative trunk conductor. Thewindings of relay 385 are connected in opposition s0 that if there is no potential on the negative conductor at this time, the relay will not operatebut V in c-asethe negative line should be in contact with some adjacent leads, relay 385 will be unbalanced and will therefore operate. .1 The.

condition for asuccessful test is therefore that relay 376 should be operated but that relays 385 and 389 should not be operated. In these circumstances no circuit is completed for the fault indicating lamps 538 540 which are wired to the fourth position of thetest switch;

It will be seen however that if relay 376 fails to come up, earth on lead 437 will be extended over backcontact and armature 378, lead 708, lead 438,1ead 748, lamp 538, to battery. Similarly if relay 385 operates a circuit is com; pleted over frontcontact andfarmature 386 and leads 706, 436 and 749 for lamp 539 and if relay 389 operates lamp 540 is lighted over armature390, lead 705, lead 435 andlead 750. A circuit is now completed from the interrupted generator 400 over lead 7 37,"frontcontact and armature 383, back contact and armature 387 armature 391 and its back contact, lead 7 38, lead 462, fourth contact in the bank of wiper 502 and said wiper, lead 33, lead 682,

front contact and armature 182, lead 683. lead 45, winding of relay 330 to battery. Relay wiper 503 and lead 447 for relay 341. Upon j the operation of relay 341, battery through re-' sistance 399 is connected at armature 342 over lead 709 through relay 389 to the positive trunk conductor anda'at armfature343 earth through the lower winding of relay, 385 is connected over lead 719 to the negative trunk conductor. .Relay 385 only operates if there is battery on the negative line, while the re sistance of relay389 and resistance 399 in series is sufliciently highto' prevent the opera;

tion of two line relaysin parallel if two po's'itive lines should be in contact, but will allow one line relay to operate if there is no contact. Relay 389 is also now operated'and;theconditions set up by this test are equivalent to the" taking of the junctionbyan A operator before it has been assigned. Accordingly if tact and lead 721 to the upper winding of relay 376. Each time relay 37 6-operates in response to the flicker the following circuit is completed :earth, armature 392 and its front Contact, armature388 and its back contact,

armature 384' and its front contact, lead 740, lead 464, niultipled contacts 5, 6 and 7 in the bankof wiper 502, lead'33, lead 682, front contact and a-rmature 182, lead 45, winding of relay 330' to battery. The operation of relay 330 asbefore eifects the stepping of thejtest switchover the nextthree positions. In each of these positions earth over wiper501 is extendedto the indicating lamp 543. i I

When the test switch reaches its 8th position the circuit of relay 341 is opened and earth is connected over wiper 501 andthe multipled 8th, 9th,'10th and 11th contacts in its bank to the junction assigned indicating lamp 544. The stepping of the test switch over the 8th and 9th contacts is effected by earth from the interrupter 400 being extended over armature 329 and its back contact lead 454 to the contacts engaged by wiper 502 whence a circuit iscompleted forrelay 330 in the usual manner. While the test switchisin its'ninth position, a circuit is completed from earthen wiper 503 to the ninth contact in its bank, lead 444, lead 745, lead'406 and wiper 626 to the assignment lead associated withthe junction.

nism with this flash. Uponeach operation of relay 376, earth is connected at "armature Accordingly the junction is assignedand the I I 377 to lead 434 over lead 704 whence'it is eX- tended tothe llthfcontactin the bank of wiper 502 and serves to operate relay 330 as before, -When the test switch reaches posit1on-12, indicating lamp 545 is lighted and a circuit is completed over wiper 503 and lead 448, for relay 344 which accordingly operates.

Thereupon at armatures 348 s3 5l,it connects g wipers 525-528 of the number-setup switch NS by way of-leads 730-733 and 449 -452,

leads 763767. lead s' 7 982, armatures 186- 189 and 'leadsf5 8 to wipers 641' 1644 of the auxiliarysecondary. distributor ASD and at armature 345' completes the following cir-' cuit: earth,winding ofrelay264, armature.

267 and its back contact, armature 345 and its front contact. lead 713, lead 470, first contact in the bank of wiper 530 and said wiper, winding of magnet 531 to battery. Moreover at armature 346 it opens the homing circuit of the numbcr-set-up switch and connects the commoning of contacts 216 to the pulsing lead from relay 264. Relays 264, 266 and 268 now interact in the manner previously described to send impulses and the switch NS is thus stepped round to etl'ectthe setting up of the digit storage relays in the impulse sender, this corresponding to the operation of the digit keys by the operator. It will be understood that the appropriate contacts in the banks of wipers 525 528 of the numberset'up switch are suitably jumpered to earth so as to effect the setting up of the test number which will secure that the test call is routed back to the routiner in a manner which will be more fully described subsequently. IVhen the switch NS reaches its 16th position after having set up a full 7-digit number, a circuit is completed from earth on the 16th contact in the bank of wiper 529. lead 768, 12th contact in the bank of wiper 504, interrupter springs 508, lead 441, lead 726, back contact and armature 313, lead 700, lead 439, magnet 50. to battery. Accordingly the magnet is energized and since the above traced circuit includes the interrupter contacts 508. the test switch is advanced one step into the 13th position. In this position the circuit relay of 344 is broken and it de-energizes, thus disconnecting the wipers of the number-set-up switch and completing circuits to cause this to return to normal under the control of interrupter contacts 532. In the 13th position of the test switch indicating lamp 546 is lighted and a circuit is completed over wiper 503 and lead 456 for relay which upon operating, at armature 356 locks to earth provided at armature 184 of the relay 180. Moreover at armature 354 it connects battery through resistance 399 and relay 389 over lead 709 to the negative trunk conductor and at armature 355 connects earth through the lower winding of relay 385 over lead 719 to the positive trunk conductor.

.This corresponds to the taking of the junction line by the A operator and causes the starting ot the sender.

The code digits set up on the storage relay groups in the impulse sender in response to the operation of the number-set-up switch are now sent out, suitably translated so as to cause the routing of the call over a special test level in a selector whence connection is established back to the routiner over the leads 481. 482 and 483. Vhen switching through is effected at the selector, a circuit is completed for relay 367 which extends as follows: battery, lower winding of relay 367, lead 7 29, normally closed springs controlled by armature 359, lead 482, negative trunk conductor, polarized relay in the junction relay set, positive trunk conductor, lead 483, armature 363 and its back contact, normally closed springs controlled by armature 358, lead 728, upper winding of relay 367 to earth. Relay 367 is accordingly now operated but the polarized relay in the junction relay set does not operate at this time owing to the current flow being in the wrong direction. Upon the operation of relay 367, at armature 368 a circuit is prepared for relay 364 and at armature 369 a circuit is completed for relay 370 and this accordingly operates in turn and at armature 371 prepares a circuit for relay 309 oy er leads 702 and 703. After the junction has been assigned, a steady earth should be applied to the lamp lead and if this condition is duly fulfilled, relay 376 will be held over its top winding. In case, however, any irregularity should have occurred so that flash or flicker pulses are still being applied to the lamp lead, relay 367 will deenergize and will thereupon complete a circuit for relay 309 which looks up and gives the alarm as will be described subsequently. Relay 370 also at armature 372 prepares a circuit for relay 374, while at armature 373 relay 304 is connected over lead 734 to the test conductor 481 extending from the selector level for a purpose which will be described subsequently.

The sending of the numerical digits from the sender will now be initiated and accordingly relay 367 will pulse in response thereto, on each de-energization completing a circuit for relay 374 which owing to its slow characteristic holds up throughout the train. Thereupon at armature 375 earth is connected over lead 432 to the 13th contact in the bank of wiper 502 and when this is removed at the end of the train of impulses the test switch is advanced one step in the usual manner to the 14th set of contacts whereupon indicating lamp 547 is lighted. The further stepping ot the test switch depends on the successful reception of the digits and also on the test which is made by means of relay 304 for guarding earth. The earth for maintaining the connection should be supplied at this time from the junction relay set and is therefore OPEI'ZIthG to shunt relay 304. If relay 304 remains deenergized, at armature 305 and its back contact earth is applied to the 14th, 15th and 16th contacts in the bank of wiper 502 over armature 375 and accordingly the test switch is advanced through these positions as the various digits are received. IVhen the test switch is advanced to its 14th position after the reception of the first numerical digit, a circuit is completed from the earth on wiper 503 and over lead 460 for relay 357 and this upon operating, at armatures 358 and 359 connects relay 367 across the leads 482 and 483. That is to say the operation of relay 357, when the test switch is advanced to its 14th position, re-

verses the connections of relay 367 to the junction from the selector level, extending over leads 482 and 483, so that in case either the negative or positive conductor is in contact with the corresponding conductor of some other junction, this reversal will prevent relay 367 from responding to impulses and the test switch will accordingly be prevented from advancing. This operation only takes place for the reception of the second numerical digit and when this has been successfully completed, the test switch is stepped so that relay 357 is no longer energized. The third and fourth numerical digits are then received in a similar manner and the test switch is accordingly stepped to its 17th position. In this position indicating lamp 548 is lighted and the earth on lead 427 is also extended over wiper 503 and lead 465 to relay 360. The operation of relay 360 at armature 363 connects busy flash battery from lead 480 to the positive lead from the selector. Moreover at armature 361 contacts 331 of relay 330 are short-cir cuited so as to prevent undue delay inthe operation of the alarm owing to the fact that this test is prolonged for three pulses of busy flash. The application of busy. flash battery over the positive lead should result in the repeating back ofa corresponding connection from the junction relay set that is to say the connection of battery to the lead coming into the routiner over wiper 627 of the junction distributor JD Hence since relay 352 is still locked up and therefore armature 355 is operated, a circuitis now completed for the lower winding of relay 385. "Upon the operation of relay 385, at armature 388 a circuit is completed over wiper 502 of the test switch for relay 330 and when relay 385 releases, this circuit is broken and accordingly the test switch is stepped. In this manner it moves a further three steps and thus advances into its 20th position. A circuit is now completed for indicating lamp 549 and also from earth on wiper 503, by way of the 20th contact in its bank, lead 458,

lead 723, front contact and armature 368,

lead 723, and winding of relay 357 to battery. The operation of relay 357 as before reverses the connection of windings of relay 367. The operation of the polarized relay by connecting battery to the negative lead eifect's the operation of relay 385 and this as before operates armature 388 though in this case earth is extended over lead 739, lead 463 to the 20th contact in the bank of wiper 504 and thence over the interrupter contacts 508, lead 441, back contact and armature 313, lead 700, lead 439,-winding of magnet 507 to battery. Accordingly magnet'507 operates and breaks its own circuit at contacts 508 and thus advances the wipers of the test switch into the 21st position whereupon indicating lamp 550 lights. The earth on wiper 503 is now extended over lead 459, winding of relay 364, lead 723,-front contact and armature 368, lead 722, winding of relay 357 to battery whereupon relay 364 operates and relay 357 is maintained operated. At armature 366 relay 364 connects ringing current from the interrupted generator over the induction coil I to the positive lead 483 whence it is extended over the selectors used and through the condenser'in the talking circuit to the corresponding contact in the bank of wiper 628 of the junction distributor JD lead 405,

windingof alternating current relay 393 to earth. If the talking condenser is in proper condition, the ringing current thus trans mitted is sufficient to cause the operation of relay 393 and this relay completes a circuit as follows: earth, front contact of armature 327, armature 394 and its front contact, lead 477, lead 752, 21st contact in the bank of wiper 502 and thence to operate relay 330 as before, so that the test switch is advanced to its 22nd position. Indicating lamp 551 now lights and relays 357 and 364 are de-energized and accordingly the current is reversed to its original-direction over the junction lineand the ringing lead and the alternating current relay 393 are disconnected. Upon therestoration of the current flow to normal, the polarized relay in the junction relay set revleases and disconnects the battery feed thereupon releasing relay 385. The following circuit is now completed: earth, armature 392 and its front contact, armature 388 and its backcontact, lead 741, lead 445, 22nd con tact in the bank of wiper 504 and said wiper, interrupter springs 508, lead 441, lead 726 back contact and armature 313, lead 700,1ead 439, winding of magnet 507 to battery. Accordingly the test switch is advanced to its 23rd position, in which position the earth on wiper 503 is extended over lead 457 to shortcircuit relay 352 and this after a slight interval releases and at armature 354 disconnects the battery feed through relay 389. Since the line relay of the junction relay set is in series with relay 389, it will also restore at this time and open the junction lamp circuit so that relay 376 should also now restore. Moreover the earth'on wiper 501 is now extended to the indicating lamp 541 to indicate the particular test in progress. When the test switch steps to its 24th position since the last two contacts in the bank of the homing wiper 506 are permanently connected to earth, it now returns to its normal position and relay 127 is again operated. The test switchis now operated in the manner previously described and earth through the interrupter 485 is connected over lead 453 to the first two contacts in the bank of wiper 502. Consequently testing for a free junction now recommences in the manner previously described and when such a junction is found the tests are carried out on it in the same way. \Vhen all the junctions accessible over the junction distributor JD have been either tested or found busy, the junction distributor J D is brought into use and tests are made on the junctions accessible from its bank. lVhen these have all been dealt with, another idle position is seized and the junctions associated therewith are routined.

In order that an indication may be obtained at any time of the number of positions which have actually been routined, the bank of switches such as SD over which wiper 612 passes is multipled to the bank of a routine indicating switch RIS as shown in Figs. 5 and 7. The routine indicating switch is stepped round, under the control of the routine indicating key RIK, the operating circuit for stepping magnet 516 being traced as follows: from battery, winding of stepping magnet 516, lead 95, contacts of routine indicating key, lead 96, armature 291 and its front contact, to earth, armature 291 being operated when the routine finish relay 285 is operated. Hence if the particular positions connected with in any position of the switch RIS have been routined, the associated indicating lamps will be lighted, and thus an indication will be given of the progress of the test. Alternatively, instead of the switch RIS it would be possible to make use of six relays each carrying ten pairs of springs and adapted to make connections similar to those effected by the switch RIS. This arrangement would have the advantage that on the ressing of the key corresponding to the key IK, all the lamps would be lighted at once.

The release alarm key RA is provided in order to enable the alarm to be disconnected after afault has been found. It will be seen that earth is provided over the normall closed contacts of this key and leads 690 and 72 to lock up the alarm relay 309 which is operated as shortly to be described when a fault is found.

The restart key RS enables the testing operation to be re-started after it has been stopped due to the distributors making a complete revolution without finding an pos tions idle and untested. At the left-hand springs of this key earth is then removed from lead 34 so as to open the locking circuit of the routine finished relay 285 while at the right-hand springs a point in the locking circurt of relay 152 is opened; consequentlv cond tlons are again restored for enabling the distributors to make a further test for positions which are idle and have not yet been dealt with.

It may be desirable in some cases to perform a continuous routine test upon a certam position or also upon a certain trunk particularly in case afault has originally been encountered and it is now desired to see that it has been properly cleared. For

a continuous routine test of a particular position, the key PCR is operated before the start key SK and the former at its left-hand springs completes a circuit for relay 119 which operates and performs the functions previously described. At the right-hand springs of the key PCB, a circuit is completed from earth, armature 117 and its back contact. back contact and armature 156, right-hand springs of key PCR, winding of relay 137 to battery. Upon operating, relay 137 at armature 139 connects earth to the stepping keys, at armature 1 10 opens a point in the homing circuit of the secondary distributors, at arma ture 141 prepares a circuit for relay 285 and at armature 142 completes a locking circuit for itself. The group stepping key GS is now operated to move the primary distributor wipers into engagement with the required secondary distributor, the circuit extending from earth, front contact and armature 139, springs of key GS, lead 67:2. lead 68, lead 168, winding of magnet 607 to battery over lead 29 to the winding of relay 233. Then the position stepping key PS is operated and each time its contacts close a circuit is completed from earth at armature 139, contacts of key PS, lead 666, lead 27, wiper 605 to magnet 610 and thence to battery through relay 233 as before. \Vhen the required position has been connected with as indicated by the lighting of the corresponding lamp, the start key is thrown and upon the operation of the start relay 115, the circuit of relay 131 is completed at armature 116 and at armature 118 a circuit (which will not become effective in this case) is prepared for stepping the secondary distributor. Upon the operation of relay 131, the test proceeds in the manner previously described on the particular position sc- I lected. When all the junctions accessible over the first junction distributor have been routincd, relays 172 and 175 are operated as previously described and relay 175 serves to transfer the stepping circuit to the second junction distributor and locks up over its own armature 178. Vhen all the junctions accessible from the bank of the second junction distributor have been tested, relay 166 is operated as before and opens the circuit of relay 175 at armature 169. \Vhile relay 175 holds up. however, a circuit is completed from earth, armature 179 and its front contact, lead 674, front contact and armature 1'70, armature 141 and its front contact, lead 64, back contact and armature 2S8. upper winding of relay 285 to battery. Relay 285 being of the two-step type operates its light armature 290 at this time, thereby shortcircuiting its lower winding over lead 31 and the lefthand contacts of the re-start key. when relay 1'75 releases after its slow period the circuit of the unction distributor magnet is opened and it accordingly steps the associated wipers thereby opening the circuit of relay 166 which also releases after a slight interval. Moreover at armature 170 the shunt earth is removed from the lower winding of relay 285 and it now operates fully thereby lighting the routine finished lamp and performing the other functions previously described. If it is desired to make a further teston the junctions in this position, the re-start key is operated whereupon at the left-hand contacts of this key the looking circuit of relay 285 is opened and the previous conditions are restored.

In case it is desired to make a continuous routine test on a particular trunk, the key TOR is operated instead of the key PCR. Thereupon at the left-hand contacts of this key a circuit is completed for relay 119 as before, while at the right-hand contacts earth from the back contact of armature 117 is extended to the winding of relay 162. Relay 162 upon operating, at armature 163 opens the pulsing circuit for the junction distributor so that this shall not be advanced at the end of each test, at armature 164 applies earth to the stepping keys and at armature 165 completes a lockin circuit for itself. 'In addition to the keys S and PS, it will be necessary inthis case to operate also the key TS which completesa circuit which is readily traceable for the magnet of the proper junction distributor. This test will continue on the trunk selected untilthe start key or the key TCR is restored.

In order to facilitate the location of faults, the key FL is provided and when this is operated acircuit is completed for relay 119 as before and also relay 143 is operated. This at armature 144 supplies earth to the stepping keys in the usual manner and opens the circuit of the visible alarms, at armature 145 opens a point in the circuit of relay 131, at armature 146 prepares a circuit for relay 180, at armature 147 completes a locking circuit for itself, at armature 148 prepares a stepping circuit for the auxiliary secondary distributor since as relay 131 will not be operated in this case no circuit is completed by it, at armatures 149 and 150 prepares connections over the auxiliary secondary distributor to the order wires extending to the position in question and at armature 151 removes earth from the second group of multipled-contacts in the bank of wiper 606 of the test switch. Since relay 180 is not yet operated in this case, this means that tests will start at position 13 of the test switch owing to the homing earth remaining connected to the first group of multipled contacts. The attendant may now if he Wishes by operating the appropriate stepping keys set the distributing switches on to any desired junction at any position and theifoperate the start key and observe from the supervisory lamps the progress of each test. When the test switch has rotated to position 13, relay .180 is operated over Wiper 505 and the test then proceeds in the normal manner. It will be noted that when the attendant is locating faults, since relay 131 does not have to be operated, he may make connection with a position which is staffed, and may if he wishes insert the jack J in the plug P and order up a connection from the operator overa particular junction. It will be seen that when the jack is inserted in the plug, .the transmitter and receiver of a handset 89 specially provided onthe routine are connected up to leads 76 and 77 and thence through the repeating coil windings to the upper and lower windings of the relay 395. This relay accordingly operates and at armature 39.6 connects up the other windings of the repeating coil in a circuit includingarmatures 149 and. 150, 192 and 193 and leads 9 and 10 to wipers 639 and 640 of the auxiliary secondary distributor ASD. Moreover, at armature 397 a point is opened in the auxiliary circuit for relay 180 andat armature 398 a circuit is completed for advancing the test switch to. its thirteenth position. The attendant will then removethe jack J thus file-energizing relay 395, which at armature 397 permits relay 180 to operate to be made on all the common apparatus only four junctions at the position need be tested;

Moreover, as previously pointed out, with the arrangement shown the capacity of the two junction distributors is 46 junctions and it is not desirable to provide more than two of these distributors. should be 50 junctions incoming to the position, the remaining four can conveniently be dealt with over contacts 1,:'4 of the firstjunction distributor, the changeover from junc tions 14to junctions 4750 being made by suitable relays. In the present instance the positions are assumed to be equipped with 50 junctions and accordingly the quick routine test is madeover junctions 47/50. For this purpose the quick routine key QR is thrown, whereupon atthe right-hand contacts of this key a circuit is prepared for relay 159. Moreover, at the left-hand springs ofthe key QR, earth is'extended over lead 687, lead 70, winding of relay 299, lead 71, armature 194 and its front contact, lead 4, wiper 645, lead 409, winding ofrelay 536 and winding of relay 535-tobattery. The relays 535 and 536 it will be understood are associated with the particular position and may conveniently be mounted In case, however, there adjacent to the battery feed relay 533: relay 299, however is located in the routiner and serves for all the positions. Upon the operation of relays and 536 the leads from the first "four contacts in the banks of wipers 625-4528 are transferred to the lamp, assignment and positive and negative conductors of junctions 47 50. Moreover at armatures 300303 of relay 299 the indicating lamp leads from the first four contacts in the banks of all the distributors J D are transferred so to connect up the indicating lamps connected with junctions 1T50 instead of those associated with junctions 14. The test now proceeds in the usual way upon the operation of the start key and when junctions l750 have been routined a circuit is completed over wiper ($29 in 5th position, lead 83, lead 662, right-hand contacts of key QR,lower winding of relay 159 to battery. Belay 159 upon operating, at armature 161 looks up over its upper winding and at armature 160 brings down relay 131. The junction distributors are then moved to the position routined contacts, that is, the 24th position of the second junction distributor, and the operation of relay 166 brings down relays 152 and 159 and allows testing to take place for the next free position on which the quick routine test is made in similar manner. Hence it is possible by this means to make a quick routine test which will test all the common equipment at the operators position and also junctions 17-50 and will only occupy a fraction of the time required for the full test. It will be appreciated that in the case of positions equipped with 50 junctions, in order to test all the junctions it will first be necessary to make the full routine test which will deal with junctions 146 and subsequently to make the quick routine test which will then deal with junctions 4750.

The arrangements for giving an alarm may now be briefly dealt with. It will be appreciated that the advance of the test switch to initiate a test is dependent on the success of the previous test and that if the test switch remains in any position except its normal one for more than a predetermined interval, the alarm will be given. A circuit may be completed for the lower winding of the alarm relay 309 over armature 377 in case the junction lamp does not receive full earth, as previously mentioned but in general relay 309 will be operated after a time interval under the control of relays 306 and 314. When relay 314 is operated, at armature 317 it connects an additional earth to the motor start lead 490 and at armature 315 connects up interrupter 316 to relay 306 and at armature 320 prepares a locking circuit for this relay. Relay 306 first operates its light armature 308 and subsequently also armature 307 thereby transferring the pulses to relay 309. If the conditions persist, relay 309 operates in due course locks up to the key RA at arma tnre 312, at armature 313 opens the circuit of magnet 507 to prevent the test switch moving, at armature 311 lights an alarm lamp, and at armature 310 connects up an alarm bcll, assuming relay 143 is not operated. It will be seen that the circuit prepared for the lower winding of relay 311 at armature 183 is opened by relay 330 each time that relay operates to step the test switch. The normally energized relays 278 and 280 associated respectively with the junction distributors and the primary and secondary distributors serve to supervise the operation of the magnets of these switches. In the case of the primary and secondary distributors, battery feed is through relay 233 and this at armature 231 connects earth to lead 58 and hence through lamp 283 to relay 314. Similarly battery feed relay 295 at armature 296 supplies earth through lamp 2t lVhen the start key is restored, earth is connected over armature 123 to lead 57 and should relays 278 and 280 not operate in due course, relay 314 would again be operated and the alarm be given so that supervision is obtained of the return of the switches to normal. The routine finished lamp 528% also obtains its battery from relay 311 so that an alarm is given in case the attendant does not at once notice the lighting of the lamp.

It will be understood that armatures 196-- 204: of relay 195 and 200213 of relay 205 are wired to the auxiliary secondary distributors ASD and ASI) in the same way as the corresponding armatures of relay 185 are wired to the auxiliary secondary distributor ASD.

\Vhat I claim as new and desire to secure by Letters Patent is 1. In a telephone system, automatic routine testing equipment for testing telephone apparatus, a hunting switch for associating said testing equipment with said telephone apparatus, means for testing idle ones of said apparatus in turn until all have been tested, and means responsive to the completion of a test on said one of said apparatus and the association of a special potential therewith for preventing the seizure of said apparatus again by said hunting switch.

2. In a telephone system, automatic routine testing equipment for testing telephone apparatus, a hunting switch for associating said testing equipment with said telephone apparatus over the bank contacts of said switch. means for advancing said hunting switch to test said bank contacts to find one associated with a piece of apparatus in condition to be tested, means for routine testing said piece of apparatus, and means for stopping said routine testing operation when no contact is tound associated with a piece of apparatus not in condition to be tested.

3. In a telephone system, automatic routine testing equipment for testing telephone

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